Last active
May 6, 2020 20:55
-
-
Save fpawel/31d65b241612cc0e5cc1985c18991a81 to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
package main | |
import ( | |
"fmt" | |
) | |
func main() { | |
//V := []string{"s", "w", "v", "t"} | |
//E := []edge{ | |
// {"s", "v", 1}, | |
// {"s", "w", 4}, | |
// {"v", "w", 2}, | |
// {"v", "t", 6}, | |
// {"w", "t", 3}, | |
//} | |
V := []string{"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n"} | |
E := []edge{ | |
{"a", "b", 10}, | |
{"a", "c", 5}, | |
{"b", "d", 30}, | |
{"b", "g", 15}, | |
{"c", "f", 10}, | |
{"d", "c", 5}, | |
{"d", "f", 3}, | |
{"d", "e", 10}, | |
{"e", "f", 5}, | |
{"e", "h", 10}, | |
{"e", "i", 20}, | |
{"e", "j", 30}, | |
{"f", "h", 20}, | |
{"f", "a", 30}, | |
{"g", "d", 5}, | |
{"g", "e", 5}, | |
{"g", "k", 15}, | |
{"h", "i", 5}, | |
{"h", "n", 20}, | |
{"i", "l", 5}, | |
{"i", "m", 5}, | |
{"i", "n", 10}, | |
{"j", "i", 40}, | |
{"j", "l", 5}, | |
{"j", "g", 10}, | |
{"k", "j", 17}, | |
{"k", "l", 20}, | |
{"l", "m", 10}, | |
{"m", "n", 15}, | |
{"m", "l", 15}, | |
{"n", "m", 12}, | |
} | |
G := newGraph(V, E) | |
G.dijkstra("a") | |
for _,v := range V { | |
fmt.Println(v, ":", G[v].len, G[v].path) | |
} | |
} | |
type graph map[string]*vertex | |
type vertex struct { | |
adj []tailLen | |
len int | |
path []string | |
} | |
type edge struct { | |
head, tail string | |
len int | |
} | |
type tailLen struct { | |
tail string | |
len int | |
} | |
func newGraph(V []string, E []edge) graph { | |
g := make(graph) | |
for _, v := range V { | |
x := vertex{len: -1} | |
for _, e := range E { | |
if e.head == v { | |
x.adj = append(x.adj, tailLen{tail: e.tail, len: e.len}) | |
} | |
} | |
g[v] = &x | |
} | |
return g | |
} | |
func (G graph) dijkstra(s string) { | |
X := make(StrSet) | |
X.Push(s) | |
G[s].len = 0 | |
for { | |
Len := maxInt | |
var v,w string | |
for x := range X { | |
xLen := G[x].len | |
for _, z := range G[x].adj { | |
if !X.Contains(z.tail) && xLen + z.len < Len { | |
v = x | |
w = z.tail | |
Len = xLen + z.len | |
} | |
} | |
} | |
if Len == maxInt { | |
return | |
} | |
G[w].len = Len | |
G[w].path = append(G[v].path, w) | |
X.Push(w) | |
} | |
} | |
type StrSet map[string]struct{} | |
func (x StrSet) Contains(i string) bool { | |
_, r := x[i] | |
return r | |
} | |
func (x StrSet) Push(i string) { | |
x[i] = struct{}{} | |
} | |
func (x StrSet) Pop(i string) { | |
delete(x, i) | |
} | |
const maxInt = int((^uint(0)) >> 1) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment